Contact terminal for vacuum tubes



M. ALDEN CONTACT TERMINAL FOR VACUUM TUBES March 17, 19311 OriginalFiled June 8, 1922 INVENTOR, M'llaiz 166,

ATTORNEY.

UNITED STATES PATENT -oFHcE MILTON ALDEN, or srnnvermnn, mssacnusnr'rs,Assumes, IBY mm: nssIen- V MEN'I'S, r RADIO INVENTIONS, me, aconroaa-rron or new ronx CONTACT TERMINAL FOR VACUULT TUBES Applicationfiled June 8, 1922, Serial No. 566,893. Renewed November 15, 1926.

This invention relates to improvements in sockets and particularly foruse in connection with wireless apparatus in which the vacuum tube oramplifier is placed.

An object of the invention is to rovide a socket structure having aseries 0 resilientcontact strips which are engaged by the terminals, orpins, of the tube when inserted in the socket. These contact strips aredesigned to bend or yield so that allof the pins will be in goodelectrical contact with the resilient contact strips. I

'Heretofore it has been found in actual practise that the lengths of thepins on the tubes vary so much that there is a possibility of one ormore of these pins not engaging the resilient contacts in the socketwith the result that i there is an open circuit leading to the tube.

It has also been discovered that the extreme lower ends of the contactpins often have a considerable quantity of solder thereon. This resultsfrom the fact that these pins are formed from' small sized tubes whichare normally open at their lower ends. The sol der which is on the lowerends of the pins comes from the operation of soldering the wireterminals, of the tubes in these pins. This results in unequal lengthsof the pins as well as inunequal electrical contacts between the pinsand the resilient contact strips.

It should also be observed that when a vacuum tube is inserted in thesocket, and turned, 1

between the sides of the pins and the upturned ,part 10 of the contactstrips a positive and good electrical contact always results. In

case of the contacts becoming oxidized it is only necessary to slightlyoscillate or partially rotate the tube a few times in its socket in oriI der to produce a bright clean contact again between the sides of thepins and the upwardly extending part of the strips.

The present invention, broadl comprises a resilient contact strip whichis ormed with an upwardly extending-bent inner end por-. tion thecontact face ofwhich is set inward from the edge of the body portion ofthe strip. This inward set portion isprovided with a curve or bend thatroduces this inward p0- sition of the part 0? the upwardly bent portionof the strip, whereby the contact strips are engaged by the sides of thepins of the tubes. This bent portion will always make contact on theside of the in of the tube if it does not on the end of t e same, whenthe tube is inserted in the socket.

Referring to the drawings:

Fig. 1 is an end and side view of a portion of one end of a vacuum tubeshowmg the resilient contact fingers showing the recessed portion andthe upwardly extending integral part.

Fig. 7 is a side elevational view of Fig. 4.

Fig. 8 is a detail view showing one of the pins of a vacuum tube engaginthe inner surface of the upwardly extendmg part of one of the contactfingers, and

Fig. 9 is a detail view showing a finger with two leaves. [j

Referring to the drawings in detail 1 designates the lamp socket as awhole, having 'an opening 1' to eceive the vacuum tube, and having abayonet joint slot 2 formed in the side thereof to receive the in 3 onthe base-part of the tube. The tu a portion only of which is shown,isine dicated as a whole, by thenumeral. 4. This tube is formed with theusual projections or contact pins 5, four of which are These pins aredesigned to make electric contact with the elastic contact strips orfingers that are attached to the base part of the socket. .These fingersare indicated by the numeral 6 and are formed with an opening 7 whichreceives the attaching bolt 8. Each of the fingers 6 is held in fixedrelation to the socket by one of the bolts 8, and further is firmly heldin fixed relation to the socket by being positioned between two ribs 13,Figure 3. These fingers are also formed with a. cut-out or recessedportion 9 to increase their flexibility and with an upwardly extendingpart 10 which is integral with the main body part 6 of the fingers. Thisupwardly extending part is connected to the part 6 by the bent or curvedportion 11, whereby the inner surface of this upwardly extending part 10stands in a plane slightly inward from the outer edge 12 of the stripand bent portion 11.

There are four of these fingers in the socket which corresponds with thefour pins 5 of the tube 4. They are arranged 90 apart, as shown in Fig.3. When the tube 4 is inserted in the socket the ends 5 of the pins 5will engage the fingers 6 as shown in Figs; 6 and 7 which will force theresilient fingers downward into the dotted line position indicated at 6'in Fig. 8. When the tube is inserted it is given a slight rotarymovement to bring the locking pin 3 into the seat of the bayonet slot 2.This operation brings each of the pins 5 against the inner surface ofthe upwardly extending part 10 with a result that contact is made withthis upwardly extending part as well as at the ends of the pins 5 butshould the ends 5 of one or more of these pins 5 not engage the fingers6 then the sides of the pins 5 would strike the inner surface of theupwardly extending part 10 and make electrical contact therewith asindicated at 5 (see Fig. 5). The upwardly extending part 10 is now .bentinto the dotted line position 10. This construction therefore renders agood electrical contact between the pins 5 and all of the fingers 6.

The contact fingers 6 are arranged staggered with their center linessubstantially tangential to the circle passing through the axes of thetube prongs and with their inner ends overlapping or offset. The sidecontacts 10 press against the sides of the prongs. They thus resist therotation of the tube as it is inserted with pin 3 in slot 2 and theytend to rotate the tube backwardly. This backward rotative tendency isprevented by the usual recess in the inner end of the usual bayonet slot2.

The position of the parts 10 are such that they will all besimultaneously forced-into the dotted line position 10' shown in Fig. 5as already stated.

From this description will be seen that I have provided a socketconstruction for receiving a vacuum tube or detector of a wiregage thesame.

The reference numeral 5 in Fig. 5 indicates the position of a pin 5 whenin place.

It should also be stated that should some of the pins 5 be wronglypositioned the flexible upwardly extending parts 10 would still beengaged by all of the pins 5.

It should be stated that when the tube 4 is inserted in the socket 2 thesides of the pins 5 will have both a wiping and a'rubbing of slidingcontact with the flexible contact strips or fingers 6. There will be awiping contact between the ends of the pins 5 and the flexible fingersand, also a wiping contact on the inner surface of the upwardlyextending portions 10 by the pins 5 when the 4 tube is rotated in thesocket 2. A rubbing or slidin sides of t e pins 5 and the inner surfacesof the upwardly extending portions 10. This sliding contact is broughtabout as the tube is pushed into the socket and then rotated to lock itin the socket. It will therefore be seen that there is both a wiping anda rubbing orsliding'contact between the pins 5 and the upwardlyextending portions or in other words there is a dual contact. The cutout portion 9 permits the portions 10 and the fingers 6 to be twistedwhen the tube is rotated in the socket.

In Fig. 9 is shown a contact finger which is composed of two thinresilient leaves 6 and each leaf may therefore be made of thinnermaterial than if the contact finger is of single thickness. The leaves 6are held in fixed relation to each other andto the socket by the bolt 8and ribs 13, Figure 3, in the same manner as the single leaf contact 6is held in position.

surface of the upwardly extending portion 10, as shown, overhangs thepart 6. This construction is not necessary as the pins 5 would engagethis portion if it did not overhang the part 6 in the exact positionshown.

The curved part 11 which connects the upwardly extending part 10 withthe part 6 of each finger permits the part 10 to readily flex or bendwhen one of the pins 5 is given a rotary movement against the part 10.The part ,10 as shown, is located in a plane that is substantially atright angles to the plane of the part 6 of the finger.

What I claim is:

1. An electrical contact device for vacuum contact will occur betweenthe tubes comprisinga member having an opening at one end for attachingthe same to a support, and an offset part against the side of which apin on the tube engages for the purpose described the body portion ofthe member being formed with a cut out part adjacent the ofi' set partto permit the part to yield when a vacuum tube is inserted,

2. A socket construction having an opening to receive a vacuum tubehaving contact pins thereon, a plurality of contact strips in theopening of the socket and designed for en:-

gagement by the extreme lower ends of the pins, and each strip having abent part which is designed for engagement with the sides of the pins ofthe tubes in addition to the engagement of the ends of the pins, whenthe tube is inserted and rotated in the opening of the socket, asdescribed.

3. A device for the purpose described comprising a strip of resilientmaterial having an integral portion offset from one side of the mainbody part of the strip, the offset portion being connected to the mainbody part by means of an inwardly extending curved part for locating theinner surface of the offset portion over the main body part of the stripand against which the sides of a pin of a vacuum tube presses and rubswhen inserted in a socket and turned.

4. A socket device comprising a tubular member for receiving a vacuumtube having contact pins thereon, contact fingers on the member forengagement by the extreme inner ends of the pins and said fingers eachhaving an ofiset portion which is designed to be engaged by the sides ofeach of said pins in addition to the engagement by the ends of the pinsto provide both a wiping and sliding contact between the ends and sidesof the pins and the contact fingers when a tube is in serted and turnedin the socket.

5. A contact strip for a vacuum tube socket comprising a body portionand a contact portion which is arranged at an angle to the body portionof the strip,-said body portion being provided with a cut-out part inone edge adjacent the said contact portion.

6. A socket construction having an opening to receive a vacuum tubehavlng contact pins thereon, a plurality of contact fingers extendinginwardly into the socket opening and designed for engagement with thelower ends of the pins, and u wardly extending portions on the contactngers adjacent the ends thereof and disposed at an angle, said upwardlyextending portions being constructed and arranged for, engagement withthe sides of the contact pins when the tube is turned in the socket.

7. A socket construction having an opening to receive a vacuum tubehavlng contact sins thereon, a plurality of contact strips isposed inthe opening in the socket and designed forengagement with the ends ofthe pins when the tube is inserted in the socket and upwardly extendingportions carried by each contact finger and arranged at an acute angletothe body portion of the contact finger, said upwardly extendingportionsbeing disposed in the path of rotation of the tube forengagement with the sides of the pins four contact pinscircumferentially spaced and projecting from the base of the contactcarrier; and four correspondingly spaced 1 spring members assembled withsaid socket and each comprising two leaf contact portions integrallyformed from one piece of sheet metal, a broad face of one of thesecontact portions engaging the extreme end of a contact pin and a broadface of the other engaging one side of a pin and exerting pressurethereon laterally thereof.

- 9. A vacuum tube socket comprising an insulating base, fourindependently mounted spring contact arms secured thereto and havinglongitudinally extending contact portions attheir inner ends adapted toengage the sides of the prongs of a tube and yie dable laterally andlongitudinally of the socket when a tube is inserted, said armsextending substantially tangentially, opposite arms being substantiallyparallel and 'ofiset on opinsulating base, independent spring armscarried thereby and insulated from each other and provided with portionsyieldable longitudinally of the socket with contact tips yieldabletransversely of the axis of the socket for engaging the sides of theprongs of a tube, means for limiting the incursion of the tube and itsprongs and-means positively limiting the rotation of the tube withrespect to the base of the socket. I V

'11. A socket having contact devices for engaging the electrodes of aninsertable device, the electrodes of the insertable device includingpinsextending longitudinally of its axis, each contact device comprisinga spring member having a portion yieldable longitudinally of the pin forengaging the end of the pin and another spring portion for engaging theside of the pin yieldable laterally of the pin and means for limitingthe movement of the insertable device when the pins are in

